Scherrer Sarah K, Gates Cassandra, Rajapaksha Harindu, Greer Samuel M, Stein Benjamin W, Forbes Tori Z
Department of Chemistry, University of Iowa, Chemistry Building W374, Iowa City, IA 52242, United States.
Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, United States.
Angew Chem Int Ed Engl. 2024 May 21;63(21):e202400379. doi: 10.1002/anie.202400379. Epub 2024 Apr 23.
U(VI) peroxide phases (studtite and meta-studtite) are found throughout the nuclear fuel cycle and exist as corrosion products in high radiation fields. Peroxides are part of a family of reactive oxygen species (ROS) that include hydroperoxyl and superoxide species and are produced during alpha radiolysis of water. While U(VI) peroxides have been thoroughly investigated, the incorporation and stability of ROS species within studtite have not been validated. In the current study, electron paramagnetic resonance (EPR) spectroscopy was used to identify the presence of free radicals within a series of U(VI) peroxide samples containing depleted, highly enriched, and natural uranium. Density functional theory calculations indicated that the predicted EPR signals matched well with a superoxide (O ⋅) species incorporated into the studtite structure, confirming the presence of ROS in the material. Further analysis of samples that were synthesized between 1945 and 2023 indicated that there is a correlation between the radical signal and the product of specific activity multiplied by age of the sample.
过氧化铀（VI）相（水铀矿和变水铀矿）在整个核燃料循环中都有发现，并作为高辐射场中的腐蚀产物存在。过氧化物是活性氧物种（ROS）家族的一部分，该家族包括氢过氧自由基和超氧自由基，它们是在水的α辐射分解过程中产生的。虽然过氧化铀（VI）已得到充分研究，但水铀矿中ROS物种的掺入和稳定性尚未得到验证。在当前研究中，电子顺磁共振（EPR）光谱被用于识别一系列含有贫化铀、高浓缩铀和天然铀的过氧化铀（VI）样品中自由基的存在。密度泛函理论计算表明，预测的EPR信号与掺入水铀矿结构中的超氧自由基（O ⋅）物种匹配良好，证实了材料中存在ROS。对1945年至2023年间合成的样品的进一步分析表明，自由基信号与比活度乘以样品年龄的乘积之间存在相关性。
